This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP third generation partnership project
BS base station
CGI cell global identifier
CM compressed mode
CSG closed subscriber group
DRX discontinuous reception
DTX discontinuous transmission
eNB E-UTRAN Node B (evolved Node B)
E-UTRAN evolved universal terrestrial radio access network (LTE)
GPS global positioning system
HO handover
IE information element
LTE long term evolution of UTRAN (E-UTRAN)
NCL neighbor cell list
Node B base station
PCI physical cell identifier
PSC primary scrambling code
RAT radio access technology
RRC radio resource control
SI system information
SIB system information block
UE user equipment, such as a mobile station, mobile node or mobile terminal
UMTS universal mobile telecommunications system
UTRAN universal terrestrial radio access network
WCDMA wideband code division multiple access
CSG cells have restricted access and only permitted UEs can make use of them. CSG cells are expected to be deployed in an uncontrolled manner, which implies that they could be located anywhere and switched on or off at any time. In addition, a planned network (e.g., a macro network, such as a cellular network) is not required to include CSG cells in its neighbor cell lists.
One typical use case is that a home base station (e.g., a home Node B or home eNB) would enable a user to make and receive calls in their home with their mobile phone, but while using a broadband connection and not the cellular network. This may be expected to reduce calling costs without incurring the inconvenience of using a land line phone.
In 3GPP Release 9 (Rel-9) there is presently an ongoing work item for enhancements to mobility towards CSG cells. This work includes connected mode mobility enhancements. To improve the customer experience of using a home Node B cell it is desirable for a call initiated on the cellular network to be transferred to the CSG cell when the user enters his or her home or otherwise comes within range of the home Node B cell.
One aspect of the foregoing is accurate identification of the correct CSG cell for the UE to be handed over to. However, the detection and identification of the correct CSG cell is made more complicated when the UE is in the connected state (e.g., is involved in a voice call or is involved in a data connection).